Accessory drive control



Filed Feb. 2, 1948 m QNH /V//// m V I I I l I l I l I I I I l l I I MN I I l I I [Ill 1 LL: l wnwwnHU HHHHHHHHHH I I I I u I I I t I I I I I I I I I I I I I luI/nhllM (1| :11: I I H I HHH HH HHHHH L l I N A a m 8 m m\ v II [III hm lllllllllllllllll Illlw I MN [Illlf ii I I .VN WT r Patented Nov. 15, 1949 UNITED STATES PATENT OFFICE ACCESSORY DRIVE CONTROL Alfred J. Mastropole, Allendale, N. 1., assignor to Bendix Aviation Corporation, Teterboro, N. J a corporation of Delaware Application February 2, 1948, Serial No. 5,757

4 Claims.

This invention relates to accessory apparatus and particularly to accessory apparatus of the type that is mechanically driven from a nonsteady source of power, as, for example, an internal combustion engine, and to improvements in the accessory drive control disclosed in U. S. application Serial No. 474,163, filed January 30, 1943 by Clinton H. Havill, :now U. S. Patent No. 2,437,- 954, granted March 16, 1948, and assigned to Bendix Aviation Corporation.

Objects of the invention are to provide improved means for transmitting and controlling the transmission of energy from a driving source of power, for the purpose of achieving a steadier power input into the accessory, and at the same time minimizing the shock effect and fracture hazards that attend fluctuation in the turning effort applied from the driving source.

In the accessory drive control of the prior device disclosed in the aforenoted U. S. Patent No. 2,437,954, both the friction disks and the spring biasing them together are located at the inboard or engine end of the pencil shaft. Thus in the event of breakage of the pencil shaft, the spring would force the parts into the back of the engine causing damage to the several parts.

An object of the present invention is to so arrange the spring that in the event of breakage of the pencil shaft, the broken portions of the pencil shaft would be biased clear of each other, with the part of the pencil shaft attached to the generator brought to a stop by action of the spring.

This is specifically accomplished by arranging the disk biasing spring at the outboard end of the pencil shaft so that in the event of breakage of the pencil shaft the engine may continue to turn its portion of the broken shaft, but the spring would pull the other portion of the shaft clear so that the portion connected to the rotor would be brought to a stop by the rubbing of a spring cup against a stationary retainer.

Another object of the invention is to so arrange the spring, that the assembly of the pencil shaft and spring may be effected with ease and without having to overcome the force of the spring, as in 1 the previous arrangement disclosed in the U. S. Patent No. 2,437,954.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

The drawing is a longitudinal view of a device embodying the invention and with certain parts broken to better illustrate the invention.

Referring to the drawing, there is disclosed therein a generator having a sectional housin 5 adapted to receive suitable field poles and field windings, for cooperation with an armature wind- '2 'ing on the armature 123, which armature winding supplies current to certain of the conductors 24 which have brush connections 25 to a commutator .25.

The housing '5 is also shown as provided with a reduced section 28 and a flanged portion 29 having a series of holes provided therein whereby the .unit maybe attached to a suitable mounting surface on the housing of the internal combustion engine or other prime mover which is to drive the generator, by suitable connections (not shown) for imparting rotation to a splined end 4| of an inner pencil shaft 42 of the generator.

The commutator '26 and the armature 23 are interlocked with a hollow shaft 5| which surrounds the inner pencil shaft 42. The inner shaft 42 is spline connected at one end to the outboard end of the hollow shaft 5|, as indicated at 53. A look ring 54 holds shaft 5| against displacement axially, in one direction, while the shoulder of a bearing 55, by virtue of its engagement with the armature 23,, prevents axial displacement of the shaft 5| .in the opposite direction. A ball bearin assembly 55 rotatably supports one end of the hollow shaft 5! while the opposite end is rotatably supported by a ball bearing assembly 51.

The novel transmission and transmission control means of the present invention comprise, in cooperation with the inner and outer shafts 52 and 5|, a yielding driving assembly including a driving plate 8|, a driven plate 82, and an intermediate friction surfaced element of suitable frictional torque transmitting material, the said member 83 is suitably fastened to the driven plate 32. The latter plate 82 is splined to the hollow shaft 5| through suitable splines 64, while the driving plate 8| is fastened to the shaft end 4|.

The clutch assembl BI, 82 and 83 is positioned in a shield-like recess 8-5 formed in the inboard end of the housing 5 land cooperates therewith in protecting the end bearing 55.

A coiled compression sprin 96 surrounds a portion of the opposite outboard end of the hollow shaft 5| and pencil shaft 42 and bears at one end upon a :plate 9?. The plate 97 is rotatably mounted at the outboard end of the hollow shaft 5|. The opposite end of the spring 96 bears upon a cup 98 which is affixed at the outboard end of pencil shaft 42 by a fastening nut 99 which screw threadedly engages the pencil shaft 42.

A retainer ca-p I covers the spring assembly and is fastened to the housing 5 by bolts Ifil. A cover cap I52 having an air spout I63 surrounds the outboard end of the housing 5 and is mounted thereon by abolt 194 which projects axially from the retainer cap Hill. A nut )5 is screw threadedly engaged on bolt I34 so as to fasten cap 12 in position.

The spring 95, as shown in the drawing, biases the pencil shaft 42 longitudinally toward the outboard end and the disk 8| into frictional driving relation with the disk 82 through the friction element 83.

Operation In operation, the turning efiort applied to the splined end 4| of the inner shaft 42 causes transmission of torque to the rotating armature 23 of the generator over two parallel pathsone path being positive and involving the inner shaft 42 to the splines 53 and from said splines to the outer shaft 5|, while the simultaneously effective but yiel-dable parallel path is constituted by the clutch assembly 8l83--82, and this latter path will operate to minimize the harmful effects of those torque impulses which are created by reason of the non-steady nature of the power development in the driving prime mover. Because of this :action of the parallel path constituted by the elements 8 l--83-82, the generator parts, and particularly the slender inner shaft 42 as well as the comparatively thin-walled outer shaft 5|, are protected against the necessity of absorbin the objectionable non-steady components of the driving torque. Moreover, the parallel path 8 |83 82 operates to dampen large amplitudes of the oscillating system constituted by shafts 42 and 5| and the rotor assembly mounted thereon, when the said system is operating at resonant frequencies. It is well to note that as the parallel path 8 l-8382 is a'frictional path, it has no natural period of vibration, while path 4 l42--5 I on the other hand, has a definite natural frequency.

The conjoint operation of both of these in parallel, therefore, serves to dampen resonate oscillation over the entire range of frequencies encountered in the widely variable speed service to which engine accessories are applied. Hence the rotor assembly may resonate without damage to the component parts such as might result if large amplitudes were created. In other words, the amplitude of vibration of the rotating assembly is prevented from rising beyond a safe maximum, which maximum may be controlled by suitable choice of damping means, within the present teaching, and by suitable adjustment of the loading of spring 96 (or any equivalent thereof which may be substituted therefor) In the prior device disclosed in the U. S. Patent No.. 2,437,954, both the friction disks and the spring biasing them together are located at the inboard or engine end 4| of the pencil shaft 42. Thus in the event of breakage of the pencil shaft 42, the spring would push the parts into the engine casing as the spring in the latter device is arranged to bias the pencil shaft longitudinally toward the inboard end of the device.

In the present invention, the improvement resides in arranging the disk-biasing spring 96 at the outboard end 53 of the pencil shaft 42 and so as to bias the pencil shaft 42 longitudinally toward the outboard end of the device. Thus in the event the pencil shaft 42 should break, the male connection 4| to the engine would continue to turn, but the spring 96 would pull the broken parts of the pencil shaft 42 clear of each other. The part 53 splined t the hollow shaft of the generator rotor 23 would then in the latter event be brought to a stop by the rubbing of the spring cup 98 against the stationary retainer l 00.

In assembling the present device the splines 53 may be engaged before inserting the Spring 96 which provides a much easier mode of assembly 1 than trying to mesh corresponding splines in the device disclosed in U. S. Patent No. 2,437,954

4 against the force of a corresponding disk-spring at the inboard end of the generator.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

1. In a machine adapted to be rigidly mounted on and driven from a pulsating power source, a housing, a rotor rigidly mounted on a stiff tube, end bearings for said tube and supporting said rotor in said housing, a resilient drive shaft extending longitudinally in said tube and in spaced relation thereto, one end of said shaft being drivingly connected to one end of said tube and the other end of said shaft extending from the other end of said tube for an external driving connection, a friction coupling including first and second disks, means drivingly connecting the first disk to said shaft adjacent the other end of said tube, other means drivingly connecting the second disk to said tube at the other end of said tube, a coil spring encircling a portion of said shaft and operatively connected between the tube and the aforesaid one end of the shaft so as to bias said shaft longitudinally toward said spring and the first of said disks toward the second disk so as to maintain a frictional driving relation between said disks, said spring so arranged that in the event of breakage of the shaft one portion of the shaft may be biased clear of the other portion and longitudinally toward the spring, and limiting means to frictionally restrain rotation of the rotor and said one portion of the shaft in the latter event. V

2. The combination defined by-claim 1 including a member operatively connecting said spring to said shaft, a cap enclosing said spring and limiting the longitudinal movement of said shaft in the event of breakage thereof, and said member arranged to frictionally engage the inner surface of said cap so as to restrain the rotation of said shaft and rotor in the latter event.

3. The combination defined by claim 1 including a plate mounted at the aforesaid one end of the tube, another plate secured to the aforesaid one end of the shaft, said spring operatively positioned between said plates for biasing said shaft longitudinally toward said spring, and a member arranged to limit the longitudinal movement of said shaft and to frictionally cooperate with said other plate to restrain rotation of said shaft and rotor in the event of breakage of said shaft.

4. In a machine adapted to be rigidly mounted on and driven from a pulsating power source, a housing, a rotor rigidly mounted on a stiff tube, end bearings for said tube and supporting said rotor in said housing, a resilient drive shaft extending longitudinally in said tube and in spaced relation thereto, one end of said shaft being spline connected to and within one end of said tube and the other end of said shaft extending from the other end of said tube for an external driving connection, a friction coupling including first and second disks, means drivingly connecting the first disk to said shaft, other means drivingly connecting the second disk to said tube, a portion of the one end of said shaft projecting from the tube, a first member secured to said one end of the shaft, a second member rotatably mounted on the aforesaid one end of said tube, a coil spring encircling the projecting portion of said shaft and positioned between said first and second members so as to bias said 5 6 shaft longitudinally toward the one end so as to maintain a frictional driving relation between REFERENCES CITED said disks, a retainer cap surrounding the spring The following references are of record in the assembly to limit longitudinally movement of file of this patent: said first member under force of said spring in 5 the event of breakage of said shaft, a cover cap ED STATES PATENTS for enclosing the one end of said housing, and Number Name Date a fastening bolt projecting axially from said re- ,4 7, Havlll Mar. 16, 1948 tainer cap for securing said cover cap thereto.

ALFRED J. MASTROPOLE. l0 

